The menisci are crescent-shaped structures of fibrocartilaginous tissue located in the knee between the condyles of the tibia and the femur. The menisci, which are actually extensions of the tibia, serve to deepen the tibial plateau to better accommodate the opposing curvature of the articulating surface of the femoral condyle.
A typical injury to the knee is a meniscal tear, which can occur, for example, when the meniscus is displaced and caught between the femoral and tibial condyles during a sudden change of movement of the knee involving a combined flexion-rotation or extension-rotation motion. Meniscal tears were originally treated by removing the meniscus in an operation called a meniscectomy. However, results showed that removing the meniscus, either entirely or even partially, resulted in degenerative arthritis and instability in the knee.
As a result of the above-described complications, surgeons began treating torn meniscus tears with suturing techniques to retain as much of the meniscus as possible. However, suturing of a meniscal tear, like a meniscectomy, was originally an open technique, requiring a large incision and consequently longer periods of rehabilitation and recovery. Advances in instrumentation ultimately led to arthroscopic meniscal repair using long needles for passing suture through the tear.
More recently, various tacks and screws have been developed for meniscal repair, which can be used arthroscopically and simplify the surgery by eliminating the need for suturing altogether. See, for example, U.S. Pat. Nos. 4,873,976; 4,884,572; 4,895,148; 4,924,865; 4,976,715; 5,059,206; 5,125,906; 5,562,672; and 5,569,252. The known tacks and associated surgical methods have various disadvantages, such as the need for special preparation of the meniscus prior to insertion.